1. Field of the Invention
The invention relates to a method to provide an integrated self-cleaning function to a squeegee which is used in Surface Mount Technology Solder Paste Printing.
2. Description of the Prior Art
There are a growing assortment of printed materials used throughout industry and especially in Electronics Manufacturing. Currently there are a host of new solder paste formulations, which happen to express high levels of adhesion to their own mass or to surrounding printing components such as metal squeegees and stencil surfaces.
A significant problem is maintaining solder paste in a known preferred position inside the printing machine. This mass of paste is transferred back and forth across a stencil surface, by alternating action of two squeegees. Typically, the solder paste does not remain in the ideal cylinder geometry, but rather becomes distorted, and stretched out when each squeegee finishes its printing stroke and raises up in the clearance position. This results in a loss of quality and dependability: the main solder paste mass, after adhering to one squeegee may be depleted of enough quantity to print again. The paste which adheres to the squeegee results in undesirable drying. It is thus most desirable to maintain the solder paste in the minimum area of surface exposure and contact with machine elements.
Cleaning the squeegee blade is a key part of the process. It is important to keep the blade free of dripping solder paste.
There have been other mechanisms to clean the solder paste, however they have not worked as desired and the mechanisms have been not been reliable. While still other cleaning mechanisms may not be able to be retrofitted to older pieces of equipment and thus increase the cost of using what might be a useful piece of equipment.